1. Field of the Invention
The present invention relates to a semiconductor device which is operated by using different voltages.
Priority is claimed on Japanese Patent Application First Publication, No. 2009-214508, filed Sep. 16, 2009, the content of which is incorporated herein by reference.
2. Description of the Related Art
In semiconductor devices, such as DRAMs (Dynamic Random Access Memories), non-volatile memory elements are used for replacing defective addresses for defective cells and for switching the internal operations. Some types of fuses, such as electrical fuses and laser fuses, are used as the non-volatile memory elements for the purpose described above. The electrical fuses can be programmed electrically, and the laser fuses can be programmed by cutting the fuses with a laser beam. Information stored in the non-volatile memory elements is read as read-out signals and the information is stored in a latch circuit.
For writing data (information) in the electrical fuses, a writing voltage required to write data is higher than the operation voltage of a semiconductor device. The semiconductor device includes external terminals so that the writing voltage can be applied to the fuses through the external terminals from outside the semiconductor device. The general terminals are used to apply the operation voltage to the internal circuits of the semiconductor device. The external terminals are arranged separately from the general terminals which are coupled to the internal circuits. This separation of the external and general terminals can avoid from the risk of applying the writing voltage to the internal circuits, so that the internal circuits are protected from breakdown.
For another example, a patent publication, Japanese Unexamined Patent Application, First Publication, No. 2007-116045 addresses a method which does not use the writing voltage through the external terminals. In the method, the writing voltage is generated within the semiconductor device.